Agitation apparatus and agitation method

Abstract

An agitation apparatus and an agitation method that ensure rapid and homogeneous agitation / mixing of fluids with a wide spectrum of viscosities from low to high levels and fluids with high thixotropy throughout an agitation vessel are provided. In an agitation apparatus, a lowest upper agitation blade is arranged to be vertically adjacent to a lower blade. As viewed from above, a line on a plane connecting a lower end portion of the lowest upper agitation blade to the center of an agitation shaft is arranged by a predetermined angle with respect to the center line of the lower blade in a blade radial direction. As viewed from the side, a horizontal cross section including the lower end portion of the lowest upper agitation blade is located below a horizontal cross section including an upper end portion of the lower blade.

Description

FIELD OF THE INVENTION[0001]The present invention relates to an agitation apparatus used in agitation processes for purposes such as mixing, dissolution, crystallization, reaction, distillation, defoaming, solvent removal, emulsification, and particulation.BACKGROUND OF THE INVENTION[0002]Conventionally, small-sized blades such as turbine blades, paddle blades, and propeller blades are often used as agitation blades of an agitation apparatus to process fluids with low to middle viscosities. To process fluids with middle to high viscosities, anchor blades or helical ribbon blades are often used as the agitation blades.[0003]However, it has been known that small-sized blades easily produce a flow boundary in an agitation vessel, which not only hampers generation of a vertically circulating flow throughout the vessel but also causes insufficient mixing when fluid with high viscosity is processed. Contrastingly, as has been known, the anchor blades or the ribbon blades cause insufficien...

AI Technical Summary

Benefits of technology

[0027]An agitation apparatus 1 according to the present invention generates a vortex flow through rotation of an agitation blade and produces a plurality of small vortex flows rotating (spinning) in the opposite direction to the rotating direction of the vortex flow. The agitation apparatus 1 also forms a vertically circulating flow having a curved section above a lower blade, which is a flow of a particular shape that cannot be observed in a conventional agitation apparatus, throughout an agitation vessel. Synergetic effects of these flows ensure rapid, efficient (low-power consuming), and homogeneous mixing of fluids with a wide spectrum of viscosities from low to high levels and fluids with a great difference in viscosity. Further, by avoiding the risk of insufficient mixing caused by adhesion of powder and decreasing adhesion of a substance to be agitated to a blade, yield is increased and cleansing and maintenance work are facilitated.

[0028]The agitation apparatus 11 according to the present invention generates a vortex flow through rotation of an agitation blade and produces a plurality of small vortex flows rotating (spinning) in the opposite direction to the rotating direction of the vortex flow. The agitation apparatus 11 also forms a vertically circulating flow having a curved section above a lower blade throughout an agitation vessel. An outer blade portion of an upper agitation blade brings about effects of scraping off and raising the fluid in the vicinity of an inner wall surface of the agitation vessel. An inner blade portion of the upper agitation blade exerts an effect of depressing the fluid in the vicinity of a central portion of the agitation vessel. The proximity of the joint portion between the inner blade portion and the outer blade portion causes effects of dividing, reversing, and merging outward flows. These effects and synergetic effects of the effects ensure rapid, efficient, and homogeneous mixing of fluids with a wide spectrum of viscosities from low to high levels, fluids with high thixotropy, fluids with high viscosity and high thixotropy, and fluids with a great difference in viscosity.

Problems solved by technology

However, it has been known that small-sized blades easily produce a flow boundary in an agitation vessel, which not only hampers generation of a vertically circulating flow throughout the vessel but also causes insufficient mixing when fluid with high viscosity is processed.

Contrastingly, as has been known, the anchor blades or the ribbon blades cause insufficient mixing due to simultaneous revolution when fluid with low viscosity is processed.

Particularly, when the small-sized blades are employed to agitate a highly thixotropic fluid, the fluid is flowable only in the proximities of the blades but not in ranges spaced from the blades, which are the vicinities of the inner wall and the bottom portion of the agitation vessel, thus causing insufficient mixing.

Also in this case, mixing becomes insufficient.

Accordingly, the aforementioned agitation blades all increase risks of insufficient mixing and incomplete reaction when such a chemical reaction that the viscosity of a substance to be processed greatly changes is brought about in the agitation vessel or a highly thixotropic substance to be processed is mixed and caused to react in the agitation vessel.

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